Thin and light is definitely where it’s at right now. Acer yesterday launched what it claims is the world’s thinnest Ultrabook, the Aspire S5. Earlier today, we reported that Toshiba says it has the world’s thinnest 10-inch tablet, the Excite X10. Now Fujitsu has launched its long awaited ‘Arrows’ handset, which it says is the world’s thinnest smartphone.

Don’t be deceived into believing for a moment that its delicate proportions mean that it’s fragile. The IS12F has Gorilla Glass protecting the 4” AMOLED 800x480px display – and if that’s not enough, Fujitsu has also made the phone waterproof, a fact demonstrated to Pocket-lint, who witnessed the phone being casually dipped into a goldfish bowl filled with water.

But beyond its thin frame and surprising durability, the specifications for this device are decidedly unremarkable. A single-core Qualcomm MSM8655 1.4GHz Snapdragon processor keeps things moving, along with 512MB of RAM, although performance out of the box is reportedly quite brisk.

Despite its sleek body, the styling is certainly something of an acquired taste. The reverse is home to a 5MP camera (compared with the RAZR’s 8MP 1080p affair), while there’s a front-facing camera of unknown resolution too. As you’d expect, there’s wi-fi (b/g/n), Bluetooth 2.1 and GPS, along with a micro-SD slot.

There’s no Ice Cream Sandwich here though – Android 2.3 Gingerbread calls the shots on this device, with no word yet on whether an upgrade will be forthcoming to Android 4.0. There is, however, a ‘Sukkiri Alarm for daily health support’; in Fujitsu’s words:

Using an accelerometer and a microphone, this alarm clock system monitors users’ body movements and breathing to determine how deeply they are sleeping. When sleep is detected to be at its lightest point, the alarm is activated, thus enabling users to start the day refreshed."

If that’s the kind of thing that floats your boat, the Arrows ES IS12F is available now… although it’s currently only available in Japan.

However, Android Community reported that a variant of the device passed through the FCC back in November – so it may only be a matter of time before it’s available in the US. However, if it costs anything like the $750 USD (¥57,800 JPY) that it’s going for off-contract in Japan, you might want to save a few bucks and get a Galaxy Nexus instead.